1. Field of the Invention
The invention relates to a device for detecting occurrence of wheeze, more particularly to a device for detecting occurrence of wheeze using biorthogonal wavelet filter banks.
2. Description of the Related Art
Conventionally, irregularity in a lung sound of a patient, such as a wheeze, can be detected using a stethoscope. Nonetheless, a doctor may not accurately detect all occurrences of wheeze using a stethoscope and the judgment made by the doctor on the occurrence of wheeze may be not objective. Additionally, such auscultation method for detecting wheeze cannot provide real time detection for those people who are prone to wheeze.
One way to address the aforementioned drawbacks is to provide a wheeze detecting device for continuously monitoring a lung sound of a patient and for detecting wheeze occurrence in the lung sound. The wheeze detecting device may be practical since the wheeze in the lung sound has a specific property, that is, the wheeze has a dominant frequency of about 400 Hertz or more and a duration of at least 0.25 second.
Generally, an algorithm named Short Time Fourier Transform (STFT) is used for processing and analyzing a sound signal. This algorithm however, involves a fixed window function that may result in difficulty in distinguishing a high-frequency signal and a low-frequency signal from the sound signal. Thus, the STFT algorithm may be unsuitable for analyzing the sound signal of wheeze.